Originally Posted by
SansAnhedral
Technically speaking, there's really no issue with a commercial tiltrotor other than the massive expense of certifying the first type, and the economics of making it profitable. The 609 point design was horrible in both these aspects (in addition to the previously mentioned poor design decisions), hence Bell selling the program - not because of some acknowledgement that "tiltrotors don't work".
Sans, I've never thought (or said) that Bell divested themselves of the 609 because "tiltrotors don't work," only that the 609 "don't work." Tilting the engines along with the proprotors is not the way to go. Back in 1955 (I mistakenly said 1957 in an earlier post), Bell's original XV-3 just tilted the rotors, not the huge-ass radial engine mounted in the fuselage. It wasn't until they switched over to turbines (XV-15) that they started running into the well-documented problems. Let's give Bell credit for doggedly trying to make it work (for decades!), but the NGCTR proves that they've given up on the 609 concept of tilting the whole shebang. Osprey seems to be doing okay as far as that goes, but...is it? The November 2023 crash of that V-22 off the coast of Japan in which the aircraft
lost the entire pylon shows us that there may still be some "issues" to be discovered. Granted, that was an accident in which the pilot ignored repeated chip lights and opportunities to land and "shouldn't have happened," but can't we say that about virtually every accident?
Wrench1 seems very optimistic about Archer and Joby achieving FAA certification of their aircraft "soon." He mentions FAR 194, but that only addresses
pilot certification. The real issue is going to be what FAR the aircraft are certified under. And that's going to be 21.17b. Which says...
For special classes of aircraft, including the engines and propellers installed thereon (e.g., gliders, airships, and other nonconventional aircraft), for which airworthiness standards have not been issued under this subchapter, the applicable requirements will be the portions of those other airworthiness requirements contained in Parts 23, 25, 27, 29, 31, 33, and 35 found by the FAA to be appropriate for the aircraft and applicable to a specific type design, or such airworthiness criteria as the FAA may find provide an equivalent level of safety to those parts.
Heh-heh-heh, "equivalent level of safety" with other certified aircraft. So, since eVTOLs are "neither fish nor fowl," the FAA is going to pull parts of existing certification rules and apply them to each individual eVTOL certification program. This should be fun! We wonder about things like crashworthiness and performance...stuff like that. Will Archer have to demonstrate how damage-tolerant their little carbon-fiber props are to bird strikes at cruise speed? I
seriously doubt that the FAA is going to make it easy on them at all. These little flying plastic eggs might seem cool to the media and investors, but I'll bet the FAA certification guys are standing on the sidelines, chuckling and going,
"Yeaaahhhh, what's Goldstein smoking? If he thinks we're going to certify that little piece of crap just like it is, he and Joby have got another thing coming."
And we shall see.